Ellipsograph



A. ARNASON Feb. 7, 1950 ELLIPSOGRAPH 2 Sheets-Sheet 1 Filed Jan. 3l, 1.945h

A. ARNASON ELLIPSOGRAPH Feb, E950 2 Sheets-Sheet 2 Filed Jan. 5l, 41945 Patented Feb. 7, 1950 UNITED STATES PATENTOFFICE ELLIPSOGRAPH'- Arni Arnason, Park Ridge, v Application January 31, 1945, Serial No; 575,489L

4 Claims.l

This invention pertains to drawing instruments, and has as its principal object the procurves, as well as curves of irregular propertiesof predetermined pattern.

- Viewed from another aspect, it is an object to provide an instrument for delineating curves, which consists of a relatively stationary leg, relatively movable leg or radius member adapted to be displaced in a rotative sense about the sta-l tionary leg, and a template or guide element on one or the other of the legs, and which serves to determine the radial adjustment of the-relatively movable `leg during rotative displacements of the latter; moreover, it is also an object to make the template or guide element adjustable in certain respects, as well as removable for selective interchange of such elements, in order that the curve pattern may be varied.

Additional and more detailed aspects of novelty` and utility relate to particulars of construction (cies- 27) lil.

and operation of the illustrative embodiment of the device described hereinafter in view of the annexed drawing in which:

Fig. 1 is an elevational view of the novel in strument in position for use;

Fig. 2 is an elevational view displaced 90 antif clockwise from that of Fig. 1, to which displacement or position the movable or tracing elemen A of the instrument has been turned;

f Fig. 3 is a top plan view looking down on Fig. 1;`

Fig. 4 is a sectional fragment, to enlarged scale of part of the stabilizing leg;

Fig. 5 is a top plan view, to enlarged scale, of the template or guide element, with associated parts shown in section;

Fig. 6 is a vertical section looking in the di rection of lines B-S of Fig. 5;

Fig. 7 is a vertical section looking in the direction of lines 1--1 of Fig. 6;

Fig. 8 is a top plan View, partly in section of a modified form of template or guide means;

Fig. 9 is a vertical section looking toward lines 9--9 of Fig. 8; v

.1; Fig. 10 is a vertical sectionl through the modi-w ed template means of Fig.v 8 showingl there@ movable` mounting means; l

Fig. llis a top planview of a modied shape of:

template for reproducing al predetermined pat tern.

`vReferringfto Fig. l, the illustrative form otfi the instrument consists of a relatively stationaryf` centering member or leg I2, pointed at its lower end I3 for'xation at a desired place on a sheetl of drawing paper or the like. I l Mounted for rotation on andabout the leg I2` is `a movable or carrier element in the form of a yoke I4, having aligned openings adjacent the extremitiesof the yoke arms, I5 and I6, through which the leg element I2 projects.

` A coil spring I7 is iittedfreelyfupon the upper. portion of -leg I2V and exerts anv expansiveeiort'v between a-stopcollar'l8, adjustably xed, as by'- set screw I9-, on leg I2, and the upper arm I5 of thel yoke, such `tlnjii'; the vlatter'is normally urgedina downward `direction,-slidab1y, on legl I2, such downward movement being limited by the engagement, under certain conditions, of yoke portion I5 with.l a trunnion. block 20 fast. on leg I2; the purpose of this block will appear hereinafter,

A relatively. movable fleg 25, constituting a.- radius and scribing.- or tracing member, is movably attached totheearrier or yoke I4. by a pail'.` of parallel arms =26 Vand 2l, each respectively secured at its end regions by pivot means 26a,

2Gb, and 210;,.2'Ib to the end portionsA I6 and I5 ofV the yoke, 'and to spaced apart points (prefere ably theupper endaand a median part) of the movable or radius leg. Thus, the movable leg is mounted for. at least two degrees of motion: ro-y tative, about the iixedv or stationary leg as a eens ter or reference point; and linear; in parallelism with theistationary leg, which latter motion, by reason vof the parallel arm attachment.2E--21.

resolves.` into aradialdisplacementwith respect to the-'stationary leg.

Movablegmemberpor leg 25 is jointed at 25o and 25D, fory example, andI carries a tracing or pencil element 25e at'its lower end,.as in the construction. of; the conventional draughtsmans:

Compa/SS.

.Assuming that the spring means I1 is normally urging the yoke or.y carrier I4 to its lowermost; position; nywhich condition the'v pencil elementt 25cfwould'be lowered `considerably downward choring point: I.3.,and pencil point. 25ciare to rest' means in the form of a template 30, having an edge portion L3I against which bears a roller sleeve 25X on leg 25; this sleeve is stopped aty its lower end by a shoulder formation on the leg proper, and at its upper end by a cap element 25Y 4) is turned up to hold the arm 50a in xed relation to leg I2.

The draftsman usually grasps the arm 50a, locates the point I3, and then sets the point 5I conveniently, so that the members I2, 50, 50a are held steady, whereupon yoke I4, and particularly arm portion I5 thereof, may be rotated to cause leg to move above leg I2 at a radial distance from the latter determined by the setting and shape of the guide means or template 30. If this template were positioned as in Figs. 1 and 2, then the resulting drawing would appear substantially i" similar to the oblate form of the disc in Fig.

the sleeve portion 25X is free to rotate in bearing against the template edge portion 3|, as for instance, when the movable leg is rotated about the stationaryleg l2.

Since the spring means I1 is constantly urging the yoke or carrier I4 downwardly, in the condition of. Fig. 1, and since .there is a constant upward pressure, in a manner of speaking, against pencil point 25c, the resultant composition of forces urges the sleeve roller 25X against the edge of the template in such manner, that if the carrier or yoke Ill be manually rotated about leg I2, leg 25 will describe a curve depending upon the shape and adjustment of the template 30; for example, if the latter be circular in shape, as shown in Figs. l and 5, then leg 25 will describe a circle, provided the template is adjusted to lie in a horizontal plane, that is, parallel with the paper surface Aon which the pencil point 25o travels, to which surface the stationary leg l2 is held substantially normal by the draughtsman. VThe construction and mounting of the template orguide means 30 is such that it may be adjusted tio-positions out of the plane, as just described, and to this end, as shown in Fig. 5, the template 3l)v is of circular form with a wide diametric slot extending close to the periphery thereof. EX-v tending transversely oi theslot, in the middle of the disc shaped template, is a pivot bar 4I of cylindrical shape in the middle, and relieved at opposite ends to it against the template disc, to which the bar is attached by means such as rivets L `rAs viewed in Fig. 6, the trunnion or pivot block 2B is pierced to receive the middle cylindrical part ofthe, pivot bar 4i so that the latter, and its at-` tached template may rock, as indicated in the dotted-iinedisplacement of the template. Block 2U is slotted as at 20X, and has threaded across the slot a tension screw 20Y which may be turned up or loosened to set or free the template for.

rocking motion, so that-the template may assume. any position from horizontal (which would result.

in the scribing of a circle by the compass part of the instrument) toY an angular position such as shown in Figs. 2 and 6 (which would result in.

thev scribing of an oblate form analogous to the shape of the template 30 as'it is viewed in Fig. 3, for example).

y In the use of this instrument, it is desirable to maintain the stationary leg part I2 as steady and straight as possible, and to this end there is provided a stabilizing member or leg (Fig. l). con-f sisting of a section pointed at 5I for engagement inthe 4draughting paper, and jointed, as at 52 to a :horizontal section 50a, which terminates in afsleeve portion 53 ttingonto the upper end ofV the stationary leg means I2. A set screwY 54 (Fig.y

3; but if the template were set in a horizontal plane, as in the full-line illustration of Fig. 6, then the resulting drawing would appear as a circle, but this circle could be ci lesser or greater radius than that of the template, depending upon the radial setting of the point 25e, as by manipulation of joints 25a, 25h, for example.

The versatility ofthe instrument may be extended in the form of construction of the template means shown in Figs. 8 through 1l, wherein provision is made for shifting the template axial-v ly, and for removing the template for substitution of other pattern forms, as will appear.

lReferring to Fig. 8, the template is in the form `of a ring, and the pivot bar BI is slotted axially at both ends, as shown in Fig. 9 with the ring tted into said ends and secured in position by means of rivets or pins 62. In other respects, the form of the trunnion or pivot block may be the same as that of block 20 heretofore described; however, the construction of Fig. l0 may also be employed, with additional advantage.

; The block 'I0 of Fig. 10 has a central plate 'II provided with a tail I2 adapted to fit into an undercut 13 in the block, which secures one end of the plate, and a combination holding and tensioning screw I4 holds the plate in position and also serves, when pulled up tightly, to grab the pivot bar 6I and nx the template in a desired position of adjustment.

Whether the form of block 28 shown in Fig. 6, or that of Fig. l0 be used, it will be clear that loosening of the tensioning screws 20Y or 14, where template means G, 5I is employed, will render it possible to shift the template in the direction of the axis of the pivot bar 6I, thus disposing the template in positions of eccentricity with respect to the leg portion I2 carrying said block 2i) o1' 76, which will resu-lt in corresponding alternations of the radial shifting of the movable or tracing leg 25. In addition, it will appear that the template 60 may also 'be rocked about this axis of shifting in the manner heretofore described or template 30, with corresponding additional components of radial variation in the movement oi the movable tracing leg as the latter follows the edge of the template in rotation about leg I2, so that the range of curvatures is further extended.`

In addition to steadying the instrument in use, the leg 5G has the further important function of affording a means for orienting the desired iigure ing figure will. then lie symmetrically about, i. e.'

on opposite sides of, this axis or line. I n Fig. Y1, the base line upon which points I3 and 5I are seento rest, could be regarded as an alignment of the sort alluded to; and, in this instance, this line would be a major axis by reason of the position in which the template 30 is there shown. If the desired gure is not symmetrical, it may nevertheless be oriented in a selected position by appropriately placing the points I3 and 5l of the compass legs.

It is desirable that the pivot 4I iit frictionally in its seat in block 20 (e. g. Fig. 6), in order that the template will remain in whatever position of adjustment it is set until the set screw ZUY is tightened.

In the embodiments thus far described, the template or guide means has been of uniformly circular character; however, it will be apparent to those skilled in the art that the edge portion of the template, for instance the edge 3| in Fig. 5, may be made of undulating character according to some predetermined requirement, and this, in addition to the possible adjustment of the template heretofore described, will expand the range of the instrument still farther.

Instead of being circular, the template may be elliptical; the guiding periphery may have parabolic or hyperbolic components; or the template disc may be of some special shape, as for example, that of the heart-shaped guide 80 of Fig. 11, which would be utilized in reproducing a heart cam, particularly in cases where such a iigure was repeatedly being drawn to different scales. Such special templates may be interchanged by simply removing the plate 1I of Fig. and substituting the desired template.

For purposes of illustration, a preferred embodiment of the invention has been described in detail, but it is not intended that the form or mode of operation of the invention shall be confined to the precise details described excepting as may be expressly provided for in the appended claims.

What I claim as my invention is:

1. In a drawing instrument of the class described, template means comprising an annulus, a pivot member disposed across the opening in said annulus, and a journal member in two pieces,

at least, said pieces being removably clamped together to embrace said pivot member and mount the template for rocking adjustment.

2. A drawing instrument comprising a relatively stationary leg, a yoke-shaped member having end portions of opposite arms of the yoke slidably engaging said leg so as to shift along the axis of said leg, spring means acting between an upper stop member on said leg and the adjacent yoke arm to urge the yoke toward the lower end of said leg, a scribing leg movable relative to said stationary leg, and parallel links pivotally joining points along the axis of said movable leg with points adjacent the ends of said yoke arms whereby to maintain said movable leg in parallelism with said stationary leg when the lower ends of said legs are on a substantially plane surface for drawing, a template on said stationary leg between the ends of said yoke arms, and a template roller on said movable leg engaged by the template and disposed on the latter leg in the region between the pivotal connections thereto of said links, and a third stabilizing leg carried by said stationary leg.

3. A compass-type ellipsograph and curve scriber comprising stationary and movable compass legs, a U-shaped member slidable on the stationary leg with the bight portion thereof moving approximately parallel to the axis of the stationary leg, spring means normally urging said U-shaped member from an upper end region toward a lower end region of the stationary leg, said movable leg being connected to said U-shaped member by means of parallel links pivotally attached to end regions of the U-shaped member and to points spaced along the axis of the movable leg, such that the latter tends to shift in parallelism with the stationary leg, said spring urging means causing the movable leg to be disposed in predetermined proximity to the stationary leg when the respective lower points of said legs are disposed on a substantially plane drawing surface, a template carried on the stationary leg between the ends of said U-shaped member, the edge region of said template being engaged by the movable leg under urgence of the spring means as aforesaid, said U-shaped member being rotatable about the stationary leg to cause the movable leg to follow said template, and scribe means carried at a lower end region of the movable leg.

4. In a drawing instrument, a stationary compass leg and a movable compass leg and means mounting the latter to move rotatably and radially relative to the former, and including a yoke carrier having the ends of its arms slidably embracing the rst one of said legs so as to shift along the axis of said first leg and also to rotate about said axis, a pair of parallel links each having an end region pivotally connected to one of said yoke arm ends and an opposite end region pivotally connected to a point axially displaced from the other said opposite end region on the other one of said legs, such that the latter is constrained to move in parallelism toward and away from the rst said leg, spring means acting on said yoke carrier to urge the latter slidable to a normally lowered position, whereby to yieldingly dispose said other leg close to the iirst leg, and a template carried on the irst leg and having a following edge portion engaged by the other leg, as a result of the aforesaid action of said spring means, in any movement of the said other leg about the rst leg, and means cooperating with said first leg for stabilizing the same in movements of the other leg thereabout.

ARNI ARNASON.

REFERENCES CITED The following references are of record in the ile of this partent:

UNITED STATES PATENTS Number Name Date 646,329 Tintanne Mar. 27, 1900 1,055,303 Elliott Mar. 4, 1913 1,128,289 Cirigliano Feb. 16, 1915 1,168,546 Odin Jan. 18, 1916 1,391,530 Diego Sept. 20, 1921 FOREIGN PATENTS Number Country Date 196,682 Germany Mar. 23, 1908 603,712 Germany Oct. 6, 1934 

